Threshold Preamp Serves Superb Banquet Of Sound

July 05, 1985|By Rich Warren.

A listening session with the Threshold FET two, series II preamplifier compares favorably to a dinner at a restaurant rated four stars by the Michelin Guide. The sound pours forth fresh and untainted, the presentation refined, the service impeccable, and the tab might put a dent in your credit rating.

The FET, like all Threshold products, fails to capture the imagination of the fast food, or in this case, the fast sound crowd. Like nouvelle cuisine, the minimalist presentation adds to the pleasure. A set of five matched knobs control all that needs adjustment; the unit isn`t sauced with switches and buttons or spiced with tone controls.

Threshold, a small company in Sacramento, Calif., specializes in a few models of exquisite electronics. It makes a handful of power amplifiers and a couple of preamps, all of which use specially patented designs innovated by Nelson Pass, founder of the company. Because Threshold builds units one at a time in limited production, the company recently sold some of its designs to Nakamichi in Japan for something closer to mass production.

Although Nakamichi represents some of the finer products coming from Japan, there`s no mistaking the Threshold-built product. Viewing the FET two resembles setting eyes upon an appetizer prepared by Jean Banchet or Paul Bocuse. The machining of the aluminum front panel, the silkscreened lettering, and the feel of the knobs lets you know this is extraordinary quality.

The FET two shows more than just a pretty face. The FET designation stands for field effect transistor, a special kind of transistor that most closely resembles the better qualities of a vacuum tube. Proper use of FETs results in the need for very few other components (and no integrated circuits). This results in extremely low noise and wide dynamic range. While many manufacturers pay attention to the concept of ``headroom`` in power amplifiers, few apply it to preamps. Headroom determines how much signal a circuit can accept before it runs short of power and begins distorting the signal.

The high level stages (after the phono section) of the FET can handle 40 volts range between signal peaks, more than some power amps. Precision in the phono stage is critical, and the FET two uses only metal film resistors and polystyrene capacitors, the highest grade for audio available. The military- grade glass epoxy circuit board shines brighter than a yellow brick road with gold plated traces and gold plated through holes. Even the input and output jacks are gold plated with Teflon insulators. No time saving plug connectors are used, every connection is hand soldered. This cursory description barely does justice to the carefully thought out circuit design and construction of this Threshold product.

The FET two includes inputs for both the common moving magnet phono cartridges and the somewhat more esoteric moving coil cartridges. Indicative of careful engineering is that the noise level of each input is about the same.

Considerable controversy exists concerning whether humans can hear the difference between preamps or amps with the same objectively measured specifications. While differences between pure electronics, like preamps, are far more subtle than between speakers or phono cartridges, they exist. Replacing my good quality seven-year old less expensive preamp with the new FET two revealed a great deal of difference although some of the subjective terms used to describe that difference belong more to poets than stereo writers.

The sound of the FET two is clear, yet exceptionally smooth. Some electronics tire the listener, yet the FET entices you to keep listening. The Threshold FET two, series II is arguably the preeminent preamp in its $1,250 price range. Of course, this is Threshold`s budget model. The company`s FET one, series II with further refinements and an extra knob or two sells for $1,000 more. No wonder the company is located on Tribute Road! Choosing that model might curtail your dining out for a few months.